In time, parts of Rajon Rondo’s game have trickled back, each making him whole again, like the player he was before.

First, the Celtics point guard had to get back in shape after sitting out nearly a year because of a knee injury, an arduous process that began with a minutes restriction that slowly increased, game by game.

Then he had to adjust to teammates he didn’t know, just as they had to adjust to him. Soon, they learned to always be ready for a pass when he’s on the court — or else risk getting hit in the face with the ball.

Along the way, the Celtics’ captain started to find a rhythm, to pile up double-digit-assist games, to be a consistent triple-double threat.

But one piece that hadn’t returned was his floater, his most reliable shot.

Attempts around the rim kept clanking off the iron. He couldn’t figure out why.

“That’s the most frustrating part of my game that hasn’t come back that I expected to be there,” Rondo said.

But late in the fourth quarter Wednesday night, with a win against the hated Miami Heat on the line, with the TD Garden crowd in a frenzy, Rondo hit two huge floaters that helped seal the Celtics’ 101-96 comeback win.

“It’s about time,” a relieved Rondo said after his 9-point, 15-assist, 10-rebound performance, his most complete game since returning to action in January.

“It’s about time.”

However, it’s important to note that the Heat were absent LeBron James, who sat out with back spasms one night after scoring 43 points against Cleveland.

“We beat the two-time defending champs [but] they were missing a fairly good player, just to qualify that,” said Celtics coach Brad Stevens.

The win helped the Celtics (23-46) snap a five-game losing streak. It also helped them win the regular-season series against the Heat, 2-1.

But without James, the Celtics had much more of a chance, and sure enough, they played the Heat (46-20) down to the wire in a back-and-forth affair that conjured up memories of their playoff battles from yesteryear.

Jeff Green hit a 3-pointer from the left wing with 2:32 left that gave the Celtics a 97-94 lead.

Then Rondo took over.

With 2:03 left, the 6-foot-1-inch Rondo faced the 6-8 Udonis Haslem in a crucial jump ball. Rondo, with his outlandish 6-10 wingspan, timed his jump well and tipped the ball toward Green.

Rondo got the ball back and found himself guarded by former Celtic Ray Allen, who faced boos from the crowd every time he touched the ball.

Against Allen, who scored 14 points off the bench, Rondo drove hard right, along the baseline, and released a floater from about 8 feet that kissed the glass and fell through with 1:44 left.

Dwyane Wade scored at the other end off an offensive rebound, cutting the Celtics’ lead to 99-96.

And then with 18.7 seconds left, Rondo connected again from the right baseline on another floater, this one from about the same distance. It turned the crowd delirious and capped the Celtics’ comeback after they had trailed by 14 points.

“Those are two tough shots,” Stevens said. “We talked earlier in the week about, you know, he’s got such a diverse game that the more floaters that he can shoot and hit, the better. And he just shot them in. He made two huge shots.”

The Celtics connected for most of the night from all over, including hitting 13 of 28 from 3-point range, which helped them overcome the Heat’s whopping 50-20 advantage in points in the paint, and a 13-0 edge in fast-break points.

“Guys made shots,” Stevens said. “I mean, we were 9 for 27 at the end of the first quarter, and we were down 12, and then we hit 60 percent of our shots the rest of the way and that’s why we won the game.”

Simple enough.

With Rondo feeding him the ball, Avery Bradley scored a game-high 23 points as he connected on 8 of 13 shots, including a career-high six 3-pointers on nine attempts.

“We just work very well off each other,” Bradley said of Rondo. “I love playing with him.”

Brandon Bass added 18 points, with 14 in the second half. Jared Sullinger had 14 points off the bench and Kelly Olynyk chipped in with 10.

The Heat shot 4 of 17 from beyond the arc, their only weakness in the box score.

Wade led the Heat with 17 points as they continued to struggle against inferior competition, losing their 11th game this season against below-.500 teams.

“That’s not good,” coach Erik Spoelstra said. “That’s not good.”

As for the Celtics, the win marked a brief reprieve from a rough season, and Rondo’s floaters were a welcome sight.

“It’s huge,” Stevens said. “Because he can get inside the defense. One of the things that’s very underrated about some of the better guards in the league is their ability to shoot floaters and get floaters off. It’s a big part of it. He’s good at it.”

Earlier this season, Rondo had said he wanted to shoot like Bradley.

What did he like about Bradley’s shot?

“It goes in,” Rondo said with a wry smile.

After a delay, so did Rondo’s floaters Wednesday. And just in time, too.